This invention is directed to a method of separating at least one polymeric component from a multi-component polymeric material. The method is particularly suitable for separating mixed polymer waste streams.
A considerable amount of mixed polymer waste is generated from lamination processes and other textile manufacturing and/or treatment processes including bi-component and bi-constituent fibers. In some situations, the polymer waste can be added back into the parent process or into another process without any treatment of the waste. However, not all polymer waste is compatible with other processes or even with one of the parent processes from which the material is produced. Typically, certain elements of the waste can be reused for certain applications while other elements of the waste can be reused for other applications. Separating the elements of the waste stream is often difficult, and in some cases may be deemed infeasible.
Separation processes typically use at least one physical property difference between components to facilitate separation. For example, solvent-based separation techniques can be used to separate one or more polymers from a waste stream by dissolving or softening one or more components of the waste stream in the solvent and filtering out the remaining solids. The mechanism may vary based upon the polymers used and the means by which the polymers are adhered together. In some scenarios, the polymer laminate may be adhered due to the thermal lamination of the polymers directly without the addition of any adhesives or other additives at the interface of the components. In other scenarios, the polymers may be adhered by adhesive lamination. In either scenario, the presence of solvents can cause the adhesive to soften or dissolve to the extent that adhesion is lost or the solvent can cause the polymers to swell to such an extent that adhesion is lost. However, solvents may negatively affect one or more of the polymers in the waste stream thereby negating the purpose of reclaiming the polymers from the waste stream.
Another separation process used to separate mixed waste streams may include chopping or shredding the multi-component waste and separating the resulting mixed waste stream by density. This method is effective in cases where the density of one or more components is higher than the density of the solvent, and/or the density of another component or components is less than that of the solvent.
There is a need or desire for a method of separating one or more polymers from a polymer waste stream without damaging or destroying the reclamation polymer while also providing an environmentally friendly means of separation that does not utilize solvents that are difficult to remove from the resulting waste streams and pose disposal concerns.